• The objective of this project was to design a shell-and-tube heat exchanger that meets the

heat requirement of 170,453 𝑤𝑎𝑡𝑡𝑠, and with consideration that the optimum overall heattransfer

coefficient is 285 𝑊/𝑚2⋅˚𝐶. The shell-and-tube heat exchanger is used to heat benzene by having hot water flow through a single-pass shell. A counter-current flow was used

because it is more efficient. The pressure-drop considerations of the benzene in the tubes

are fixed at a maximum velocity of 1.2 m/s. Due to space limitations, the length of the heat

exchanger must not exceed 6 m. The tubes used for the design are ¾ in OD 17 BWG tubes.

Segmental baffles, or 25% cut baffles, were included to ensure that the water will flow

across the tubes, thus enhancing the heat transfer. The target overall heat-transfer

coefficient, 𝑈, is 10-25% higher than the optimal 𝑈 to ensure that the heat requirement of

170,453 𝑤𝑎𝑡𝑡𝑠 is met. Copper tubes were used because of its high thermal conductivity,

𝑘𝐶𝑢 = 380 𝑊/𝑚⋅˚𝐶.

Our calculations conclude that the optimal tube arrangements for the design of the heat

exchanger are 2 tube-passes with 45 tubes. Using a square pitch tube orientation, the

inner diameter of the shell was found to be 0.337 m, and the baffle spacing was 0.8 times

the inner diameter of the shell. The length of the tubes was 2 m, and the velocity of the

benzene in the tubes was 0.24 m/s. Using these specifications, our outer and inner

convection heat-transfer coefficient, ℎ𝑜 𝑎𝑛𝑑 ℎ𝑖, were 997.3 𝑊/𝑚2⋅˚𝐶 and 519.8 𝑊/𝑚2⋅˚𝐶

respectively. Since ℎ𝑖 was lower than ℎ𝑜, the overall heat-transfer coefficient based on the

inside of the tube, 𝑈𝑖, was used to represent 𝑈. Hence, 𝑈𝑖 was calculated to be 323.1 𝑊/𝑚2⋅˚𝐶

and the available overall heat of the heat exchanger, 𝑞, was 170,430 𝑤𝑎𝑡𝑡𝑠. This meets our

heat requirement of 170,453 𝑤𝑎𝑡𝑡𝑠, and our overall heat-transfer coefficient is 10-25%

higher than the optimal 𝑈.

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